Instead of Xeres being the god of Madness, Insanity etc... I'm going to use him as the god of Truth and Foresight. A massive change you might think but I think it could work. The world of Twylos will still perceive Xeres as the god of all the bad stuff as the main role he plays in the world is to punish people who tell intolerable lies. Priests of other cults who abuse there position and corrupt others under them will soon find themselves falling to the Curse of Xeres.

Very rarely there will be a true follower of Xeres who is a prophet/truthsayer/oracle, however unfortunately these are often taken as madmen due to nobody knowing the truth about Xeres.